Messages in this thread | | | Date | Mon, 12 May 2008 15:18:05 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH/RFC] spi: Change modalias from a pointer to a character array |
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On Fri, 09 May 2008 11:32:28 -0600 Grant Likely <grant.likely@secretlab.ca> wrote:
> From: Grant Likely <grant.likely@secretlab.ca> > > Currently, 'modalias' in the spi_device structure is a 'const char *'. > The spi_new_device() function fills in the modalias value from a passed > in spi_board_info data block. Since it is a pointer copy, the new > spi_device remains dependent on the spi_board_info structure after the > new spi_device is registered (no other fields in spi_device directly > depend on the spi_board_info structure; all of the other data is copied). > > This causes a problem when dynamically propulating the list of attached > SPI devices. For example, in arch/powerpc, the list of SPI devices can > be populated from data in the device tree. With the current code, the > device tree adapter must kmalloc() a new spi_board_info structure for > each new SPI device it finds in the device tree, and there is no simple > mechanism in place for keeping track of these allocations. > > This patch changes modalias from a 'const char *' to a fixed char array. > By copying the modalias string instead of referencing it, the dependency > on the spi_board_info structure is eliminated and an outside caller does > not need to maintain a separate spi_board_info allocation for each device. > > If searched through the code to the best of my ability for any references > to modalias which may be affected by this change and haven't found anything. > It has been tested with the lite5200b platform in arch/powerpc. > > Signed-off-by: Grant Likely <grant.likely@secretlab.ca> > --- > > drivers/spi/spi.c | 2 +- > include/linux/spi/spi.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 1ad12af..bdf1b70 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -229,7 +229,7 @@ struct spi_device *spi_new_device(struct spi_master *master, > proxy->max_speed_hz = chip->max_speed_hz; > proxy->mode = chip->mode; > proxy->irq = chip->irq; > - proxy->modalias = chip->modalias; > + strncpy(proxy->modalias, chip->modalias, KOBJ_NAME_LEN); > > snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, > "%s.%u", master->dev.bus_id, > diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h > index 387e428..38a080b 100644 > --- a/include/linux/spi/spi.h > +++ b/include/linux/spi/spi.h > @@ -82,7 +82,7 @@ struct spi_device { > int irq; > void *controller_state; > void *controller_data; > - const char *modalias; > + char modalias[KOBJ_NAME_LEN]; > > /* > * likely need more hooks for more protocol options affecting how
I'm not really able to work out if this is a needed-in-2.6.26 thing. I assumed "not".
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